Methods for scanning a laser beam on a workpiece's surface is known in the art. In the field of ophthalmic medicine, for example, photorefractive keratectomy (PRK) is a procedure for laser correction of focusing deficiencies of the eye by modification of corneal curvature, generally accomplished by use of a 193-nanometer wavelength excimer laser beam that ablates away the workpiece, i.e., corneal tissue, in a photodecomposition process. An example of devices known in the art includes that described in commonly owned U.S. Pat. No. 5,980,513.
Once an ablation pattern is determined for a particular eye, the laser beam must be moved quickly and accurately. It is also desirable that the laser beam shots remain parallel to each other when the beam is translated in an X-Y plane. Further, since laser beam motion is typically achieved using mirrors, which must be replaced at certain intervals, it is desirable that a laser translation system have components that are easily and quickly replaceable, most desirably in the field. In addition, it is desirable that such components, when replaced, remain aligned in the field and retain alignment during use.
It is known to use flexural pivots in a parallelogram shape to maintain mirror optics in a perpendicular configuration relative to a surface for achieving lateral motion. However, in previously used systems, the center shift experienced by the pivots during flexion has created an undesirable angular deviation sufficient to obviate the use of such pivots in a laser scanning application requiring the level of accuracy in the ophthalmic arena.